The installation of wall-to-wall carpeting often involves stretching the carpet to obtain a smooth, flat installation. This generally entails installing tack strips around the perimeter of the area to be covered with carpet adjacent to the walls of the area. The carpet is then rolled out in the room, usually over some padding, rough cut and seamed. One side of the carpet is attached to the tack strip along one side of a room and then stretched to the other side where the carpet is attached to an opposing tack strip. This process removes any wrinkles or creases in the carpeting, resulting in a flat, safe and visually appealing carpet installation.
During the above-described method of installing carpets, the carpet installer uses various tools for stretching the carpet. A common tool is the power stretcher. The power stretcher is generally composed of three parts: (1) a head, which is typically constructed from a head having a plurality of downwardly extending carpet gripping members for anchoring the head on the carpet; (2) an anchor for anchoring the stretcher; and (3) a transfer section, including a lever arm mechanism for transferring the force delivered by a downward stroke of the lever arm to the head to stretch the carpet. Power stretchers are typically provided with telescoping extension members which can be used to increase the length of the transfer section as needed.
There are two general types of power stretchers. The first type, typified by U.S. Pat. Nos. 4,084,787 to Kowalczyk, 639,718 to Dexter, and 549,044 to Zander, all stretch the carpet towards the anchor point which is typically secured by nailing to the floor or by inserting a blade behind a tack or tackless strip which has been nailed to the floor. The second type, which is the type most commonly used, is typified by U.S. Pat. No. 4,230,302 to Crain Jr. The Crain power stretcher includes a head with downwardly extending carpet securing pins, a transfer tube section, and an anchor. A sliding bar is attached at a first end to the rear of the head. The second end of the sliding bar telescopes into a first end of the transfer tube. The transfer tube can be extended by means of telescoping extension members which freely accept the sliding bar. An anchor is attached to a second end of the transfer tube for engaging a wall. A pivoting handle is attached to the rear of the carpet engaging head, and extends towards the anchor. In between the ends of the handle is located a linkage that pivotally connects the handle to the transfer tube. When the handle is depressed towards the transfer tube, the head is forced away from the transfer tube and the wall engaged by the anchor.
The kind of carpet being installed dictates the amount of force used to stretch the carpet. High quality carpeting, with very strong, dense, multiple layer backings typically require a higher amount of force to stretch. Economy carpeting, with minimal, single layer backings, require a lower force to stretch. In either case, applying too much force during the stretching process can damage the carpet and/or result in an unsightly installation.
Unfortunately, most conventional power carpet stretchers do not include any device for indicating how much force is being applied to the carpet being stretched. U.S. Pat. No. 3,311,347 to Thompson discloses a stretching device with two stretching heads separated by a threaded force exerting means, and including a pressure responsive scale, such as a bathroom scale, for measuring the force applied to the carpet by the threaded force exerting means. However, the scale in the '347 patent is disclosed as having a range from 0-300 pounds. Such a device would not be adequate for stretching carpets or measuring the force applied to stretch carpets in a modern installation where it is not unusual for forces well in excess of 300 pounds and up to as much as 1,000 pounds to be applied during stretching.
Accordingly, the need exists for a device for accurately measuring the force delivered by a conventional power stretcher for carpets, and which can be mounted to an existing power stretcher without the need to modify the power stretcher.